multisim simulation error voltage

[mstepp]

I am evaluating Multisim11 with this circuit.  I was thinking of the LM317, but the LM117 was in the library.  It looks like it simulates adequately when the switch is on, but not when it is off (23KV from a 24V supply).  What am I doing wrong?  Thanks.

[Tayyab_R]

Hi mstepp,

I looked into your circuit and it turns out there is a bug in the specific voltage regulator you are using. Instead of the LM117HVH, use the LM117H and with that I am seeing much better results. I will report the problem to our R&D. Sorry for the inconvenience.

[mstepp]

Thanks.  I don't see an LM117H in the library for my evaluation version of the software.  Where do I get that?  Do you have the LM317 (or L or M versions) in your library?

It also looks like Q2 does not have enough gain.  When the switch is on, VCE seems much higher than it should be.  The model shows the appropriate gains in the electronic parameters, but a note there says that the parameters displayed are meaningless for the simulation.

Thanks

[Tayyab_R]

Hi mstepp,

I have attached the modified circuit to this post. You can right-click the LM117H and select Save Component to DB. Then you can add this component to your user database. As far as the transistor goes, the simulation models for all the components are developed by the manufacturers so they usually try to make them as realistic as possible. If there is more than one simulation model available, they are shown on the bottom right under Model manufacturer/ID in the Select a Component Window. You can try different models if available.

Hope this helps.